Abstract: To improve the precision of casing collapse pressure calculation,the variance analysis of the full scale collapse test data of 213 casings is conducted with statistical method.The effects of outer diameter/wall thickness,material yield strength,ovality,eccentricity and residual stress on the casing collapse resistance are analyzed in this paper.The results show the ratio of diameter and thickness and yield strength are the main parameters of influencing the collapse pressure of casing,and the decreasing of the casing collapse resistance is a random process with the increasing of ovality,eccentricity and residual stress.And the casing simulation analysis of various combinations of the location of ovality,eccentricity and residual stress under external pressure is performed.From the simulation results,it is concluded that the casing collapse pressures differs greatly between different combinations.In the end,a new casing collapse calculating formula is put forward which gives the more accurate prediction of casing collapse,the accuracy can meet the requirement of application.

Key words: casing, collapse resistance, variance analysis, finite element analysis, full scale test